Charles ii



C. H. PURDY.

ROTARY CHAIR.

Patented Apr.' 22, 18901l f' N l .J /f f( (No Model?) WI/'67a fossesUNITED STATES PATENT OEEIGE.-

CHARLES H. PURDY, OF MICHIGAN CITY, INDIANA, ASSIGNOR OF ONE-I^IALE TOHENRY IV. JOHNSON, OE SAME PLACE.

ROTARY CHAI R.

SPECIFICATION forming part of Letters Patent No. 426,323, dated April22, 1890.

Application led August 3, 1889. Serial No. 319,698. (No model.)

T all whom it may concern:

Be it known that I, CHARLES H. PUEDY, a citizen of the United States,residing at Michigan City, in the county of La Porte and State ofIndiana, have invented a certain new and useful Improvement in RotaryChairs, which is fully set forth in the 'following specification,reference being had to the accompanying drawings, in which- Figure lrepresents a vertical central section, and Fig. 2 a plan view, of thechair with the seat and spindle attached thereto removed.

My invention relates to that class of rotary chairs and stools which canbe raised and lowered, so that the seat can be adjusted to any desiredheight; and my invention relates to the devices which enable me torevolve the seat without raising or lowering it, and also raise or lowerthe seat by turning the seatsupporting device.

It also relates to the above-named devices, in combination with aballbearing, all constructed and operated as hereinafter fully setforth.

In the accompanying drawings, A represents the chair or tool seat.

B is a block so connected to the seat as to turn with it. I have shownthe block B attached rigidly to the seat A in the drawings, which wouldbe the simplest construction in revolving stools; but in constructingrotary chairs-such as office-'chairs-the block B would be connected withthe seat A, either by springs or other well-known devices used in rotaryoffice-chairs, but always so connected that the block B would revolvewith the seat A. The block B is provided with a spindle C, as shown inthe drawings.

D is an annular bearing-plate, which su pports the entire weight thatrests on the seat A, and is provided with a hollow shank or spindle E,through which the spindle C passes, and in which the spindle C has acontactbearing at or near its ends. The shank or spindle E also has anexterior screw-thread F, which engages with an interior screwthread inthe nut G, which is rigidly connected to the legs II ot the chair orstool'.

I is a V-shaped groove in the bearing-platc D, and J is acorrespondingly-annular V- shaped groove in the block K are hardenedmetal balls of the required size to fit in the V-shaped grooves I and Jand prevent the block B from coming in contact with the plate D, but atthe saine time allow them nearly to touch, so that very little dust willreach the balls K.

The entire weight of persons sitting on the seat A rests on the halls K,which are supported upon the annular plate D. The balls K, resting inthe V-shaped grooves I and J, prevent the entire side strain produced inmoving the chair from being thrown upon the spindle C, and as the seat Ais revolved the balls K roll in the grooves I and J, and the spindle Cturns in its bearing without the seat being raised or lowered.

Then it is desired to raise or lower the seat, the person takes hold ofthe hand-wheel L and revolves the plate D, with its hollow shank orspindle E, when, by means of' the screw-threads F, the bearing-plate Dwill be raised or lowered, the seat A being correspondingly raised orlowered.

The hand-wheel L may be provided with suitable projections or handlesfor turning the annular plate D as desired.

In the operation of my invention a person sitting upon the seat A canturn about without raising and lowering the seat, as in ordinaryrevolving stools or chairs. The seat is, revolved readily and held in aiirin position on account of the balls K supporting the seat, as abovespecified. By reaching around beneath the seat the person can turn thesupporting-plate D with its screw-threaded cylindrical shank and raiseand lower the seat to any desired position.

M are pins put through the end of the spindle C to hold the seat inposition upon its supports when the chair or stool is lifted to be movedabout.

Having thus fully described the construction and operation of myinvention, what I claim as new, and desire to secure by Letters Patent,is-= l. In a revolving chair or stool, the interiorly screw-threaded nutor block G, to which the legs are attached, the bearing D, provided ICQwith an exteriorly screw-threaded hollow l shank having a smoothinterior, and a spindle C, having a smooth exterior, fitting loosely inthe hollow shank and rigidly connected to the seat for raising andlowering the seat Without turning it, substantially as and for thepurposes specified.

2. In a revolving chair or stool, the seat A, block B, attached to theseat and provided 1o with the spindle C, and an anti-frictionballloearing, the bearing D, provided with an

